From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4ABB623D7FB for ; Tue, 9 Sep 2025 12:35:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757421301; cv=none; b=Q38kVkU7Ubp9wp/txa+rEjf4ymABDYRSj+XwhwbQFGuTFmzVeYdyTP5RcYqDCY8R6lzAOojbRX3z4r6n3Z0UmCDr+QyFbpENkf+3OJd/sRVxBzqYfkGuragkjFBiUDmEzlMhalbBZgdyoRD1hiVZfe3lc8mVtJTl7otff8sbyXU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757421301; c=relaxed/simple; bh=omKdstwL77RPXtZIEzJXBRsX/3EnRMsRF7nu2mdihMs=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=fAvBhE4r6asF8TFEzyZBDiGVO+S1mMIBmNqd9fP0eSvRi4kOm3UVhPnuxilTlKFkxHYwH3PoMFYTw+TS2/ZtTO51H2T1OCfwQWZKxQEFjH1fGZSYEkO7WLPtaTARUFc0dxXkz3CG8kJujw2mkizc6H9NkVHm0q3Ev7qtZLEZJTg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=FMQItb42; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=X2e6Mxz1; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="FMQItb42"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="X2e6Mxz1" From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1757421298; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=omKdstwL77RPXtZIEzJXBRsX/3EnRMsRF7nu2mdihMs=; b=FMQItb422JjDZeZx2wo/yCybobtGu+LVkiDJBBYUJzEqLxEWzMqkyWtZwb5DOBXRJ+rVFL LwGOZjpUBu7Ubu4KXiUJS88MrsvLbZuHX/hM9wy2+V9D+LTJSnNh4te2AoJ8Jg4fE6ZER5 iZSoDADPLVBHRh4TV9yrRPuIfrJnfGVZR3tH2mNmDTl7PLzbr7cR5aSpzOpvThyq/EjSwX UdNy4NWiFpp7Ozl4kdN0puRq+QvnZIkrShSdSPgdpxrddHUsoWod4Aau3IHpVNLZBBYy2j Q1f5WjdzKJ4aNJCqnkv3qx4aLZtoLInZdrUZQvhm8uo+yHDv0DHjD7N2RReAvA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1757421298; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=omKdstwL77RPXtZIEzJXBRsX/3EnRMsRF7nu2mdihMs=; b=X2e6Mxz177hfO5TSwM33+qiApv+YbFcIySdJrQSWGZKtIj4sLLoTle6qVyIuR5B+E2Ai/2 NRcLFU6krTwoAvDA== To: Marc Gonzalez , linux-rt-users@vger.kernel.org Cc: Daniel Wagner , Leon Woestenberg , Steven Rostedt , Thomas Gleixner , Sebastian Andrzej Siewior , Clark Williams , Pavel Machek , Luis Goncalves , John McCalpin , Frederic Weisbecker , Ingo Molnar , Masami Hiramatsu Subject: Re: Unexplained variance in run-time of trivial program In-Reply-To: <0d87e3c3-8de1-4d98-802e-a292f63f1bf1@free.fr> References: <5f7496eb-bf62-4cc9-bef0-9cae97a93dca@free.fr> <841polf13z.fsf@jogness.linutronix.de> <42c5fb53-d423-41a5-80d9-557ff2a3e804@free.fr> <84ldmsevcm.fsf@jogness.linutronix.de> <3f1d4229-a95c-4d99-a98f-249d9e488b32@free.fr> <84ldmp8ewv.fsf@jogness.linutronix.de> <3fe55967-b4fa-4bc1-ae2b-58b5d1bbf3ea@free.fr> <3220a6ab-19e5-4705-865a-1e1c37b67ccf@free.fr> <0d87e3c3-8de1-4d98-802e-a292f63f1bf1@free.fr> Date: Tue, 09 Sep 2025 14:40:57 +0206 Message-ID: <84ms73kdn2.fsf@jogness.linutronix.de> Precedence: bulk X-Mailing-List: linux-rt-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On 2025-09-09, Marc Gonzalez wrote: > I captured a full trace of this occurrence with > echo *:* > $TRACING/set_event > cat $TRACING/per_cpu/cpu$CPU/trace > trace.$CPU ... > But there is absolutely NOTHING traced between 4606.628019 & 4606.811832. I recommend using the function tracer: # echo function > $TRACING/current_tracer It should not affect your timings for pure-userspace code. This should catch any unintentional kernel activity. John